The invention relates to an actuator effecting an approach pre-stroke and a working stroke for operating a tool, comprising an actuator body with at least two pistons slidable therein, either in the same direction or in two opposite directions, when extracted from the actuator body, namely a pre-course piston and at least one working piston joined to a working rod actuating the tool.
The tool will be designed to perform welding, stamping, stapling or any other assembly operations in which the tool or, conversely, the workpiece, is transported by a robot or a manipulator to form the different assembly points within the welding range. If the robot or the manipulator carries the workpiece to be assembled, the tool will be fixed on the ground. If the robot or the manipulator is carrying the assembly tool, the workpiece or workpieces to be assembled will be fixed relative to the ground. The invention applies to situations where the tool is provided with a closure system enabling the workpieces to be assembled to be clamped between two arms or two articulated jaws, the clamping action (working stroke) being effected following an approach pre-stroke of the tool.
A pneumatic (or hydraulic) actuator of the known type mentioned above, designed for the aforementioned applications for example, may be used in the context of the technique described below with reference to FIG. 1 of the appended drawings.